What is Congenital Hypothyroidism?

Mala and Ashok (not their real names) were relieved that Mala’s delivery had gone smoothly, and a healthy three kg baby was in her arms. However, the next day they got a shock when the pediatrician informed them that the baby’s thyroid test had come abnormal, and would need to be repeated for confirmation. Mala knew that blood had been taken from the umbilical cord after it was cut, for some screening tests. But, how could her baby be hypothyroid? No one in the family had a thyroid problem!

The pediatrician explained to the anxious parents (and grandparents) that one in 1000 to 2400 newborns is born with a deficiency of thyroxin. During the pregnancy, the mother could compensate by providing the hormone to the baby. Once outside the womb, the baby could not depend for this supply.

“So? Why is it so important?” asked Mala.

“The brain continues to develop for two years after birth. Without enough thyroxin, it cannot develop properly. This means that the baby will become mentally retarded.”

“What?! The baby is absolutely fine, she’s crying normally, moving all her limbs, feeding normally. She does not look mentally retarded!” exclaimed a disbelieving Ashok.

The doctor reassured them, “The baby is normal now, but if she does not get thyroxin, then she would gradually get affected. Her milestones would start slowing down.”

“Well, we can start thyroxin at that time,” argued Mala. “Why give her a drug now?”

“The damage to the brain cannot be undone. If treatment is started late, the mental retardation does not get reversed. There is no further damage, but the retardation that has happened, stays. That is why early detection and early replacement is so important. The brain damage has to be prevented, it cannot be treated.”

Dadi was still skeptical, “No one in our family or Mala’s has a thyroid problem. She did not take any drugs or wrong foods during pregnancy. Then how did the baby get hypothyroidism?”

“In some babies, the thyroid gland does not develop properly or cannot function properly. So, it cannot make all the thyroxin needed. Mostly, this is not inherited, or caused by medicines or foods.”

The baby’s blood was taken at the age of three days, and tested for TSH and T4. Again the TSH was over 100 uIU/ml and the T4 was very low. The paediatric endocrinologist was consulted and he advised a thyroid scan to be done. It showed a ‘lingual thyroid’. She explained that during pregnancy, the foetus’ thyroid gland is formed at the base of the tongue, and then migrates to its final position in the neck. The baby’s gland had failed to do this, and was therefore small and unable to cope. The baby would be started on thyroxin immediately, so that her brain and body development could proceed normally.

Nana was curious, “Why did you test our baby? She looks quite normal. How did you know she had a lingual thyroid?”

“We did not. We screen each and every newborn. Because we know that hypothyroidism cannot be detected by clinical examination at birth in over 90 per cent newborns, and the damage caused by late treatment is irreversible, it is critical that every newborn be screened.”

“How long do we have to give the baby thyroxin?” asked Mala.

“This gland will not be able to work normally, so baby will need replacement all her life,” pointed out the pediatric endocrinologist.

“All her life!! She will be fat and ungainly, and infertile!”

The doctor could not help laughing a little at the extent to which Mala’s eyebrows rose. “Not at all! Please remember you would be giving her enough thyroxin to compensate for her deficiency. So she will be absolutely normal.” Then she paused and added, “Well, she would have normal thyroid function. If you overfeed her, and indulge her with chips, ice cream, pasta and cold drinks, then she will get as fat as any other normal child!”

Nani said, “Don’t worry on that score! Mala was not allowed junk as a child, so I doubt she will spoil her daughter. But the fact remains she will be on a drug all her life.”

The pediatric endocrinologist corrected her, “We are replacing what she should have made herself. So it is not an artificial drug.”

Ashok looked up neonatal screening. It was described as an essential public health responsibility offered for conditions which:

Are common

Can be detected easily and efficiently

Can be detected at a stage when they would not be ordinarily clinically detected

Can be treated effectively

Cause morbidity if untreated

When he read more, he realised why congenital hypothyroidism (CH) fits the bill so completely.

It is common; CH was described as occurring in one in 2,500-4,000 newborns, but he found that in South Asia it may be almost 1:1,100-1,200.

Thyroid hormones, TSH and T4, are easy to test and readily available. In remote areas, blood can be collected on special filter papers and posted to a lab. TSH is usually quite high in babies with CH.

Most affected newborns appear normal at birth, and can be diagnosed only by testing the blood.

Treatment is effective, simple and inexpensive.

If treatment is started within two weeks of birth, the child’s IQ is normal, but if treatment gets delayed, the baby has permanent mental retardation. CH is the commonest cause of preventable mental retardation.

In fact, screening for CH therefore is one of the most cost effective measures. Neonatal screening for various disorders, including CH, is done in all babies in developed countries. Ashok realised that while some large hospitals in India have begun universal neonatal screening, the vast majority of hospital delivered babies are still not being tested.

Mala’s baby was advised thyroid tests at regular intervals to make sure she was getting the correct dose. On a follow-up visit a few months later, waiting outside the paediatric endocrinologist’s office, Mala began chatting with a couple also waiting to see the doctor. She found that their son also had CH, but it was detected when he was six months old. “Now he is two years old, and we have never missed a dose since it was detected, but he is definitely a slow developer. He may never be normal!” said his father sadly. The couple looked enviously at Mala and her baby, when they heard how her CH had been detected at birth, and thyroxin started by the age of one week.

That day Mala and Ashok realised how lucky they were. Immediately they decided to do something about this. They started an e-campaign to educate pregnant women about the need to have their newborn’s thyroid test done, emphasising that testing should be done for every single newborn, not just a few high-risk babies. It is important for the parents to know, because in India, newborn screening is not mandatory. They know that the more parents and doctors are made aware of this, the more babies can be saved from a terrible fate, yet so preventable.

Their question is simple: “Why should timely CH detection be a matter of luck? It is every baby’s birthright!”